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Great Basin Naturalist

Volume 56 Number 4 Article 11

11-21-1996

Helminths of the southwestern , Microscaphus, Woodhouse's toad, Bufo woodhousii (Bufonidae), and their hybrids from central Arizona

Stephen R. Goldberg Whittier College, Whittier, California

Charles R. Bursey Pennsylvania State University, Shenango Valley Campus, Sharon, Pennsylvania

Keith B. Malmos Arizona State University West, Phoenix

Brian K. Sullivan Arizona State University West, Phoenix

Hay Cheam Whittier College, Whitter, California

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Recommended Citation Goldberg, Stephen R.; Bursey, Charles R.; Malmos, Keith B.; Sullivan, Brian K.; and Cheam, Hay (1996) "Helminths of the southwestern toad, Bufo Microscaphus, Woodhouse's toad, Bufo woodhousii (Bufonidae), and their hybrids from central Arizona," Great Basin Naturalist: Vol. 56 : No. 4 , Article 11. Available at: https://scholarsarchive.byu.edu/gbn/vol56/iss4/11

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 56(4), © 1996, pp. 369-374

HELMINTHS OF THE SOUTHWESTERN TOAD, BUFO MICROSCAPHUS, WOODHOUSE'S TOAD, BUFO WOODHOUSII (BUFONIDAE), AND THEIR HYBRIDS FROM CENTRAL ARIZONA

Stephen R. Goldbergl , Charles R. Bursey2, Keith B. Malmos3, Brian K. Sullivan3, and Hay Cheaml

ABSTHAcc--The gastrointestinal tracts, lungs, and urinary bladders from 77 Btlfo microscaphus, 61 Bufo woodJuJUsii, and 8 of their hybrids were examined for helminths. One of trematode (Glypthelmins quieta), 1 species of ces­ tode (Distoichometra bufonis), and 5 species of nematodes (Aplectana incerta, A. itzocanensis, Rhabdias americanus, Physaloptera sp., and Physocephalus sp.) were found. The greatest prevalence (41%) and mean intensity (231.7) were recorded for Aplectatul incerta in 8u1o woodhousii. It appears hybrids harbor fewer parasites than either parent species.

Key words: helminths, Hufo mieroscaphus, Hufo woodhousii, hybrids, Arizona.

The southwestern toad (Bufo microscaphus Although there are reports of helminths trom Cope, 1866) is presently recognized as 3 allo­ B. microscaphus (Parry and Grundmann 1965) patrie subspecies: B. m. califomicus Camp, 1915, and B. woodhousii (Trowbridge and Hefley 1933, which occurs in coastal southern California Brandt 1936, Walton 1938, Reiber et al. 1940, and northwest Baja California; B. m. microsca­ Kuntz 1941, Kuntz and Self 1944, Rankin 1945, phus Cope, 1866, found in southern Nevada Fantham and Porter 1948, Frandsen and Grund­ and , Arizona, and New Mexico; and B. m. mann 1960, Parry and Grundmann 1965, Camp­ mexicanus Brocchi, 1879, which occurs in the bell 1968, Brooks 1976, Jilek and Wolff 1978, Sierra Madre Occidental of central Mexico Baker 1985, Hardin and Janovy 1988, McAllister south to Durango (Price and Sullivan 1988). et al. 1989), populations of these trom Ari­ Woodhouse's toad (Bufo woodhousii Girard, zona have not been examined. Concern over 1854) is recognized as 4 subspecies: B. w. wood­ declining populations (Heyer ct al. housii Girard, 1854 occurs in eastern Montana 1994) has increased interest in the possible nega­ and North Dakota, south through the plains tive effects of parasites on toads. The purpose of states to central Texas and west of the Rocky this paper is to report on helminths ofthese toads Mountains from Idaho south to Colorado and and their hybrids trom Arizona. Arizona with isolated populations in west Texas, This investigation ofparasitism in these toads southeastern California, and along the Oregon­ addresses a hypothesis of hybrid zone theory Wasbington border; Bufo w. australis Shannon and species boundaries. The hypothesis that and Lowe, 195.5 is found from central Colorado populations ofhybrid individuals with reduced through New Mexico and Arizona to Sonora, fitness act as barriers to gene flow between 2 Mexico, and along the Rio Grande drainage into species separated by a hybrid zone (Barton 1979, south\:vest Texas and adjacent Mexico; Bufo w. 1980) could have several mechanisms. One velatus Bragg and Sanders, 1951 is restricted mechanism, increased parasitism of hybrids, is to northeast Texas; and B. w. fowleri Hinckley, evaluated in this study. Two previous studies of 1882 is widespread throughout much of the parasitism in vertebrates are split. Hybrid mice eastern United States south to the Gulf Coast (Mus musculus X Mus domesticus), specifically and west to eastern Texas (Behler and King 1979). backcrossed hybrids, had greater numbers of The toads examined during this study, B. m. cestode and nematode parasites than either rnicroscaphus and B. w. australis, are known to parental species (Sage et al. 1986). Prevalence hybridize in Arizona (Sullivan 1986, Sullivan of monogenean parasites for hybrid minnows and Lamb 1988). (Barbus barbus X Bm'bus meridionalis) was

1Department of Biology. Whittier Colleg<\ Whittier, CA 9O(-'()f!, 20eparlmenl of Biology. Pennsylvania State Univel'5ity, Shenango Valley Campu.'. 147 Shcnango Avenue. Sharon. PA Hi146, 3Depal'tmcnt ofUfe Sciences. Box 37100. Arizona State University West. Phoenix. A7. 85009.

369 370 GREAT BASIN NATURALIST [Volume 56

positively associated with the percentage of B. and ASU accession numbers are given in rneddionalis genes (Le Bmn et al. 1992). Ifwe Appendix 1. find that hybrid toads have greater parasitism Toads were anesthetized by immersion in 1 than each toad species, then parasitism may be gil solution of tricaine methane sulfonate (MS­ a mechanism that reduces hybrid fitness and 222, Sigma, St. Louis, MO). Heart, liver, thigh contributes to the barrier between these 2 toad muscle, and kidney were removed and frozen speCIes. for future genetic analyses. Toads were then fixed in neutral-buffered 10% formalin and MATEmALS AND METHODS moved to ethanol for storage following proce­ dure outlined by Simmons (1987). The body One hundred forty-six toads were collected cavity was opened by a longitudinal incision in Arizona during 1991-1995; snout-vent length from vent to throat, and the gastrointestinal (SVL) was measured to the nearest mm after a tract was removed by cutting across the esoph­ minimum of 6 mon in 70% ethanol storage. agus and rectum. The esophagns, stomach, small Toads were identilled using a hybrid index (HI) intestine, large intestine, lungs, bladder, and and advertisement call structure, if available. coelom were examined under a dissecting Following Blair (1955), Sullivan (1986), and Sul­ microscope. No helminths were found in the esophagus or urinary bladder. All helminths livan and Lamb (1988), we evaluated the degree were removed and identified using a glycerol of expression of 4 characters to generate the wet mount. Specimens were placed in vials of HI score for each toad, dark ventral pigmenta­ alcohol and deposited in the U.S. National Par­ tion, cranial crest, dorsal shipe, and pale colora­ asite Collection, Beltsville, Maryland 20705, (0, tion across the eyelids. A numerical score 1, (accession numbers, Appendix 1). 2, 3) was assigned for each of the following 4 character states: present, weakly present, very RESULTS AND DISCUSSION weakly present, or absent. A score of 3 was assigned for the presence of dark ventral pig­ Prevalence, site, and mean intensity for each mentation, cranial crests, a dorsal stripe, and parasite are given in Table 1. Terminology is in absence of a pale bar across the eyelids. This accordance with Margolis et al. (1982). One yields scores near 12 (4 X 3) for B. woodhousii species of trematode (Glypthelrnins quieta and 0 (4 X 0) lor B. microscaphus. Numerous [Stafford, 1900]), 1 species of cestode (Distoi­ other studies of hybridization hetween toad chometra bufonis Dickey, 1921), and 5 species species have used a morphological hybrid index of nematodes (Apleetana. ineerta Caballero, such as this (Volpe 1959, Meacham 1962, Hen­ 1949, Aplectana itzoeanensis Bravo Hollis, 1943, rich 1968, Zweifel 1968). All toads from sites of RlwhdUis arnericanus Baker, 1978, Physalnptera sympatry with scores of 4 through 8 were con­ sp. [larvae only], and Physoeephnlus sp. [larvae sidered hybrids, as were all toads with interme­ only]) were found. It would appear li'om Table diate advertisement calls. Intenllediate calls are 1 that both species and their hybrids are sus­ typical of hybrid toads between these species ceptihle to inlection by the same parasites. The (Sullivan 1995), and calls have long been used greatest prevalence (41%) and mean intensity to delimit hybrid toads of other species pairs (231.7) in our study were recorded for ApleetarUl (Blair 1956, Zweifel 1968, Green 1982). Sev­ incerta in Bufo woodhousii. Thirty-four of 77 enty-seven Bufo microscaphus (mean SVL = (44%) Bufo rnieroscaphus (30/67, 45% males; 61.4 mm + 8.7 s, range 34-86 mm, 67 males, 4/10, 40% females), 51 of 61 (84%) B. wood­ 10 females); 61 Bufo woodhousii (mean SVL = housii (45/53, 85% males; 6/8, 75% females), 74.5 mm + 8.8 s, range 49-91 mm, 53 males, 8 and 4 of8 (50%) hybrids (3(1 males, 1/1 female) females), and 8 hybrids (mean SVL = 60.5 mm were infected. Males and females ofhath Bufo + 8.4 s, range 45-72 mm, 7 males, 1 female) rnicroscaphus Cr = 1.17, 1 df, P > 0.05) and were examined. Kruskal-Wallis test statistic B. woodhousii (x'l = 2.79, 1 df, P > 0.05) did (45.92, 2 df, P < 0.001) indicates significant not differ significantly in helminth prevalence. difference in SVLs for the samples examined. There were too lew fCmale hybrid toads for M'ter examination all specimens were deposited chi-square analysis. There was statistical differ­ in the collection of Arizona State ence in abundance of nematodes between B. University (ASU), Tempe. Collection localities microscaphus and B. woodlwusii (x2 = 23.72, 1996J ARIZONA TOAD HELMINTHS 371

TABLE 1. Prevalence, mean intensity (range), and location of helminths from Bufo micro8caphus, B. woodhousii, and their hybrids from Arizona.

Bufo microscaphus Bufo woodhousu Hybrids (N ~ 77) (N ~ 61) (N ~ B)

Prevalence Intensity Location Prevalence Intensity Location Prevalence Intensity Location Parasite species (%) (range) (%) (range) (%) (range)

TREMATODA Glypthelmins quieta 1 LO b 2 2.0 b 13 La b

CESTODA Distoichometra bufonis 14 2.9 (1·6) b 38 2.0 (1·8) b 13 LO b

NEMATODA AplectaM incerta 1 156.0 b.o 41 231.7 (23·564) b.o Aplectana itzocanensi.s 19 75.0 (1·373) b.o 26 43.2 (1·204) b.o 25 LO 0 PhysaWptera sp. (larva) 16 5.5 (1·31) a 5 6.0 (2-U) a 13 LO Physocephalus sp. (larvae) 1 104.0 d " Rhabdias ameri.camw 5 2.0 (1·3) e 38 21.7 (I-Ill) a - stomach, b - small iutestines, c - hU'ge jnte~til1es, d - cysts on stomilch wall, e - lungs.

1 df. P < 0.001). When the intermediate record for Aplectana incerta and Physaloptera prevalence (50%) ofthe small hybrid sample (N sp. Bufo w. woodhousii has been reported by = 8) was included in the chi-square calcula­ Baker (1985) to host Aplectana itzocanensis. tion, statistical significant difference remained Bufo microscaphus X B. woodlwusii hybrid is a (x'l = 23.97,2 df, P < 0.001). new host record for Distoichometra bufonis, To test for difference in infection rate, we Glypthelmins quieta, Apwctana itzocanensis, used a Kruskal-Wallis rank-order statistic be­ and Physaloptera sp. Glypthelmins quieta in cause of the great variation in mean intensity Arizona is a new locality record. of parasites harbored by B. microscaphus, B. With the exception of GlyptJwlmins quieta, woodhousii, and their hybrids (116.3, 19.4, 1.3, all helminths found in our study have been respectively) and the relatively small sample of previously reported in other desert toads from hybrids (N = 8). This test revealed that hybrid Arizona (Table 2). GlyptJwlmins quieta has pre­ individuals had fewer parasites than do indi­ viously been reported in Bufo microscaphus viduals of either species. Examination of more from Utah (Parry and Grundmann 1965) and in hybrids could strengthen this result. Subsequent Bufo woodhousii from Nebraska (Brooks 1976). It is widely distributed in anurans in North work to determine the importance of age, America (Prudhoe and Bray 1982). The distri­ genetic factors, nutrition, and ecology would bution of Distoiclwmetra bufonis, Aplectana also help to establish the significance ofhybrid incerta, A. itzocanensis, Physaloptera sp., and ancestry on parasite levels. Rlwbdias americanus in North American toads Infected appeared healthy; i.e., none has previously been discussed (Goldberg and were emaciated and there were no gross abnor­ Bursey 1991a, Goldberg et al. 1996). Apwctana malities. Thus, the presence of helminths did incerta, A. itzocanensis, and Rhabdias ameri­ not appear to adversely affect the populations canus have direct life cycles; Distoichometra of B. microscaphus, B. woodhousii, or their hy­ bufonis, Physaloptera sp., and Physocephalus brids. In a study on Couch's spadefoot (Scaphw­ sp. have indirect life cycles and require at least pus couchii) from Arizona, Tinsley (1990) found 1 intermediate bost (Anderson 1992, Smyth no correlation between presence of the trema­ 1994). Because these helminths are not species tode Pseudodiplorchis americanus and mating specific and occur in a variety of , success, although the presence ofP americanus the distribution ofintermediate hosts may play reduced fat reserves during hibernation. an important role in determining the distribu­ Bufo microscaphus is a new host record for tion of those parasites with indirect life cycles. Distoichometra bufonis, ApwctatUl incerta, A. The conditions responsible for determining itzocanensis, Physocephalus sp., and Rlwbdias distribution of the parasites with direct life americanus. Bufo woodhousii is a new host cycles have yet to be defined. 372 GREAT BASIN NATURALIST [Volume 56

TABLE 2. Helminth community ofdesert toads from Arizona.

Helminth Host Reference

TREMATODA Glypthelmins quieta 8ufo micruscaphus This study B. woodhousii This study Pseudodiplorchis americanus Scaphiopus couch# Tinsley 1990

CESTODA Distoichornetra hufonis Bulo cognatus Goldberg and Bursey 1991a B. microscaphus This study B. punctatus Goldberg and Bursey 1991b B. renfannis Goldberg et al. 1996 B. WOOdJlOusii 'Ibis study Scaphiopus couchii Goldberg and Bursey 1991a Nem.atotaenia dispar Rufo ab;arius Coldberg and Bursey 1991a

NEMATODA Aplectana incerta Bufo microscaphus This study B. retiformis Goldberg et al. 1996 B. woodhousii This study Scaphiopus couchii Goldberg and Bursey 1991a Aplectana itzocanensis Rufo alvarius Goldberg and Bursey 1991a B. cognatus Goldberg and Bursey 1991a B. microscaphus This study B. punctatus Goldberg and Bursey 1991b B. retiformis Goldberg et al. 1996 B. woodhousu This study Oswaldocruzia pipiens Bulo alvarius Goldberg and Bursey 1991a B. cugrurtus Goldberg and Bursey 1991a B. punctatus Goldberg and Bursey 1991b B. retiforrnis Goldberg et al. 1996 Scaphiopus couchii Goldberg and Bursey 1991a Physaloptera sp. (larva) Bufo alvarius Goldberg and Bursey 1991a B. cognatus Goldberg and Bursey 1991a B. microscaphus This study B. retiformis Goldberg et al. 1996 B. wuodhousii This study Physocephalus sp. (larva) Bufo alvarius Goldberg and Bursey 1991a B. microscaphus This study B. retiforrnis Goldberg et aI. 1996 Rhabdias arnericanus Bt/fo alvarius Goldberg and Bursey 1991a B. cognatus Goldberg and Bursey 1991a B. microscaphus This study B. retifonnis Goldberg et al. 1996 B. woodhou,~ii This study

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